In state of the art networks, such as GSM, WCDMA, LTE, and WiFi, distinctively different signals are transmitted from each network cell. In LTE, for example, each cell is associated with a PCI (physical cell identity) that is a locally unique signal used to derive sequences used for e.g. demodulation and synchronization signals. Further, positioning reference signals (PRSs), in e.g. LTE, are derived from the PCI. In any given position, the sum of all locally unique signals, such as PCIs and/or PRSs, typically create a fingerprint that is unique to that particular location.
In such state of the art systems, so-called “over the top” (OTT) and/or third party actors can utilize this property in order to provide positioning services, such as location based advertising, based on network finger-printing. By comparing e.g. Global Positioning, GPS, information available in certain wireless devices with network fingerprints of the same wireless device, the network fingerprints may be mapped to geographical positions, and be used for positioning of other wireless devices which do not have GPS functionality or has turned off the GPS, but still have access to the network fingerprint information. FIG. 1 illustrates a wireless communication system comprising access nodes 101-103, and a wireless device 104. The access nodes all transmit positioning reference signals associated with a respective identity, in this example 17, 56 and 9. The wireless device 104 obtains the signals, e.g. performs measurements on the signals, and the combination of the result of the measurements form a network fingerprint 105. This fingerprint 105 may be obtained by an OTT Positioning Service Provider 106, which then may build a database of network fingerprints and use them for positioning of wireless devices and selling the positioning information to anyone who desires it.
That is, this entails e.g. that a number of OTT actors may track the movements of individual wireless devices, and also sell this information to other parties, neither of which may be in the interest of the users of the tracked wireless devices. It may further not be in the interest of the operators, which provide the signals enabling the network fingerprinting, that third party actors map network fingerprints and make money out of selling positioning information related to their subscribers, typically without compensating the operators which make large investments in the network enabling the positioning. In other words, network builders may not have an interest in investing in networks which provide a positioning value to others which do not contribute to the development, maintenance and/or financing of the network.
However, the users in a system may still want to have the possibility of high accuracy positioning based on signals provided in the network. For example, some users may want access to high accuracy positioning, e.g. indoors, or elsewhere, where GPS signals are not available.